Stiffening member for shoes and the like



mama Mar. 4,1941

PATENT orr ca STIFFENING MEMBER FOR SHOES AND THE rm s. Balon, Arlington, is. 1., and Harold s.

' assignors Holt, W

ilmingflm, DeL, sstio Corporation, Wilmington, Del., a corporation of Delaware No Drawing- Application February 4, 19:9, .Serlal No. 254,604

10 Claims- (CI. 38-77) 3 invention relates to stiflening members for shoesand the like and, more particularly, to boxtoes and counters made from a web of fibrous material impregnated with a thermoplastic sub-.

5 stance. I

Material for stiffening members is commonly made by-impregnating a suitable fabric with a thermoplastic composition. Blanks of suitable size and shape cut from the impregnated goods. usually skived to a tapered edge, are shaped into conformity with the shoe last by being softened by heat and, while still soft, stretched in place over the last. stiffening material of this type is designated as heatsoftening, to distinguish it from those which are softened for lasting .by being moistened with solvent or with waterand whichiard designated as solvent-softening and water-softenin respectively.

Heat-softening stiffening members are ordinarily softened for lasting by being placed on a socailed "steamer", i. e., a box or tray with a perforated bottom set over a bath'of boiling water. It is, accordingly, necessary that a heat-softening stiffening material shall become effectively softened at the ordinary temperature of this device, which will range between about 80 and 190 0.. and it is further-essential that the blank shall then retain its softness during the brief period,

. amoimting ordinarily to from 10 to 15 seconds,- I which is required for completing the operation of the pulling-over machine. At the same time, it is essential that the box toe or counter, as a part of the structure of the finished shoe, shall not be subject to deformation by heat in the course of ordinary and prolonged wearing, or of storage and display.

It is further desirable that stiffening members used in the construction of ordinary dress shoes, as differentiated from work shoes having the soso called "safety toe feature, shall have adequate rigidity and'toughness without'being excessively thick which would impair the appearance of the shoe as a whole. Further requirements are that the material shall not be subject to deterioration with age, and that it shall at no time either in the course of the construction of the shoe enduring its subsequent service, cause stain or other damage to the leather or fabric with which it is associated in the shoe, and also that it be not subject to damage either by immersion of the shoe in water or by protracted contact with moisture or with perspiration from the feet of the wearer.

It is-an object of the present invention to provide improved stiffening material of the heatsoftening type. More specifically, it is an object 1 1 of the invention to provide such a material presenting a combination of desirable properties not heretofore associated with stiffening materials of the impregnated heatssoftening type.- namely, a

material which is softened adequately by the tem- 15 perature of the steamer and retains its softness during the subsequent ordinary Oper tion of lasting, which is satisfactorily form-"stable,"i. e., is free from deformation by heat at temperatures-of ordinary service, storage and display, which, in a 20 thickness acceptable for dress shoes, has notable strength and toughness and rigidity, which does not strain or otherwise damage adjacent materials in the shoe, and which is not'subject to deterioration with age nor to'softening or dete- 25 rioration by immersion in water or by prolonged exposure to warmth and moisture in service. Other objects of the invention will be apparent from the description given hereinafter.

The 'above objects are accomplished according 30 to the present invention by the use, as a stiflening member for shoes and the like, of a web of fibrous material such as fiannel,'felt, paper, and similar fibrous material, impregnated with a composition comprising essentially beta-naphthoi- 85 modified rubber, of beta-naphthol content between 10-30%, by weight, and a compatible aux-- iliary component, the composition having a temperature of plasticity of -90" C. and a softening point of -100 C. 1

The term temperature of plasticity" is used herein to denote that temperature atwhich in the A. S. T. M. ring-and-ball test (1336-26. A. S. '1. M. Standards, 1927111. 496) the ball starts to sink into the heated impregnant being It 45 has been determinedthat this temperature sub- 1 stantially coincides with the lowest temperature at which the usual stiffener impregnated with the impregnant in question is softened sufflcieiitg ly to be lasted. In ordinary practice, the temperature of plasticity should not be higher than the temperature of the steamer, i. e., between 80-100 0., and, preferably, between 70-90 C. The term softening point" is used herein to denote the temperature of the impregnant determined as the softening point in accordance with the A. S. '1. M. ring-andballl test (D36-2'6, A. S. T. M. Standards, 1927, II, 496) i. e., the temperature of the impregnant at the moment when the sinking ball arrives at the-bottom of the test container.

The beta-naphthol-modified rubber, which may be produced in accordance with the method set forth in United States Patent 2,158,530 to Ira Williams and entitled Thermoplastic derivatives of rubber," may be graded in accordance with the proportion of vbeta-naphthol with which the rubber ha been brought into reaction. It is believed that not necessarily all of the beta-naphthol is actually chemically combined vwith the rubber but any amount in excess of that which is actually chemically combined, nevertheless remains closely associated with the rubber and has the effect of modifying its properties.

The naphthol-modified rubbers contemplated for use in the present invention are those in' which the beta-naphthol content ranges between 10-30%, by weight, a beta-naphthol content of 20% being preferred. The term "beta-naphtholmodified rubber" is used hereinafter throughout the specification and claims to denote the betanaphthol-modified rubber such as may be obtained .by the process disclosed and claimed in said United States Patent 2,158,530, and' which has a beta-naphthol content between 10-30%, by

weight. It has been found that naphthol-modi- I fiedrubbers outside this range are not adapted for the purposes of the present invention.

Beta-naphthol modified rubber possesses remarkable toughness and strength. At ordinary temperatures it is rigid rather than rubbery, resembling hard rubber (ebonite) but differs therefrom in being capable of being melted without serious decomposition. The -high"softening point and the high viscosity of this material in molten condition precludes the use-of betanaphthol-modified rubber by itself as an impregnant for shoe stiffening materials since it does not become mobile enough at practical tempera-' .tures to permit acceptable impregnation of fibrous material by ordinarily available methods.

It has now been discovered that auxiliary ingredients maybe combined with beta-naphthol-- modified rubber to give a composition highly advantageous as an impregnant for shoe stiffeni that is, by combining the beta-naphthalmodified rubber with auxiliary ingredients a composition is obtained with a-softening point and stability, and of improving aasawe v A modified rubber that will have a temperature of naphthol-modified rubber and the viscosity of the melt, of decreasing the temperature of plasticity without unduly decreasing the formr the toughness and, particularly, the flexibility. I

Modifiers for beta-naphthol-modified rubber may be defined as substances which have the a same general effects as the plasticizers but a much more marked eifectwupon the form-stability which necessitates limiting their proportion in the mix to a lower percentage than is necessary with the plasticizers.

Extenders may be defined as substances characterized by being compatible with beta-naphthol-modified rubber and by being fusible therewith to a homogeneous mixture but by being without beneficial effect upon the toughness and flexibility of-the beta-naphthol-modified rubber and, in fact, tending to impair these properties somewhat. The extenders do not substantially alter the form-stability of the mixture and some are without substantial influence on the softening' point and the temperature of plasticity whileothers tend to lowerthese to some extent.

The'proportion of auxiliary component to be used in the impregnantmust give a composition having a temperature of. plasticity between ceeding the temperature, around 190 0., at which they are safe from decomposition.

Since the effect of individual auxiliary ingredients on the beta-naphtholemodified rubber varies,'it is not possible to define except within '40 filo- C. and a softening point between 75-.100

approximate operative-limits the proportions of considered. However, in the light of, the'discussion given hereinafter, together with the numerous examples,- those skilled in theart will be able to formulate readily preferred specific impreggant compositions within the scope, of the invenon. v

plasticizers, modifiers, and extenders, generically In the following examplesillustrati ng specific impregnant compositions according tothe invention, and throughout the specification, all proportions are given by weight unless otherwise stated. The examples, are grouped. in tables as follows: I

Table I, Examples 1 to 1 3-use of plasticizer as sole auxiliary ingredient;

Table 11, Examples 14 to 28 use .ofmontan wax (either a plasticizer or an extender depend- 4 aasasae Table V.=-L'ontinued Example No.

'iob

militia?" FX. Limed rosin (196 F.) Black East India gum Temperature of plasticity 0.)..." 75 70 74 80 70 74 84 Softening point 0. s s1 11 e1 11 1s 92 @6 Example No.

Nap nthol-modifled rubber: v

100 100 100 100 100.. 25 100 100 'st 'iiifio'io 166 400 525 648 an 600 240 see 100 15s o 74 10 1s 11 so 1g '30 88837677888171 Table VI toe thereby softened again before bed-lasting.

The box toe material remains soft for quick andv Example easy lasting and conforms to the last, so that reheating and relastlng are not necessary; The material is, however, capable of being reheated 76 7 and relasted.ifnecessary. No solvent is used in softening or lasting, but tFggggifQffiffRfffff'f ffii j the lining adheres satisfactorily to the box toe. w Montanwax n 2 The inside of the lining is not stained.

gag- 5 It will be understood that all of the above ex- Gumar"FX 100 amples are merely illustrative and that the infiiet ttitt i ???f.2:33:12053313113113: Z3 Z3 vention broadly comprises, s a stiffener for shoes and the like, a web of fibrous material impreg l x m e h m1 nated with an impregnant composed of betai t igg g hg gggii 3 522 5 2 :33 ig naphthol-modifled rubber and an auxiliary comimpr'egnated products of the invention: ponent' t impregnant havmg temperature v 4 of plasticity of ill-90 C. and a softening point Example 78.A mixture of: of 754cm c ts Instead of the wool-cotton felt used in Example rubber (beta'naph' 78, other webs of fibrous material may be used thal- 20%) 100 such as other varieties of felt, paper, flannel, AX 15 canvas, duck, felted cellulose fiber such as that Mfl Wax 192 sold under the name Krafelt, and the like. 311 rosin 461 It has been found that, when only one. of the is heat wi h Stirring at until three classes of auxiliary ingredients is to be mogelleolls- This 9 mixture is used to employed, the proportionsshould generally be, pregnate an 8 ounce/square yard wool-cotton felt per 100 arts of beta naphthol-modifled rubber, l'the dipping proc s e impre n d Sheet respectively: Of, plasticizers, between 33 and 100 0 is stripped at 0.039 inch between heated rods and Parts; f modmembetween 13 and 1 parts;

then calendel'ed to inch and almwed t0 and of extenders, between 300 and900 parts. 30X we blanks 0f the desired Shape an Whereauxiliary ingredients of more than one Si e are S p 011$ the Sheetof the three classes are used as a composite comf skim we blank is softened by ponent of the impregnating composition, the being exposed to steam at 100 C. Oil'thfl steamer range of operative mixtures cannot expressed for fr m 20 t 60 Seconds and is n placed accurately in terms of limiting proportions of we e lining loth and doubler cloth ofthe the three classes of auxiliary ingredients although sh upp r a d t whole ass y f at r, the beta naphthol-modifled rubber content of cloth, and box toe is pulled over on a pullingthe impregnating composition should be not less over machine, The box toe blanks soften quick than 10% and not more than 88%.

'lyon the steamer and become only slightly As indicated in the examples,'coumarone insticky. The box pulls over smooth and conforms dene resins of liquid or semi-liquid character to the last in the usual manner. When the shoe have been found useful as plasticizers in the presreaches the operation of bed-lastinglthe toe end ent impregnating compositions. These include is inserted into a beehive steamer and the box Barrett Company's Cumar AX" (melting range 20-30 C.) and Cumar BX (melting range 35- 45 C.) and Neville Company's Neville x-r. Montan wax is also a useful plasticizer but may be used in proportions up to 900 parts per 100 parts of beta naphthol-modified rubber, functioning as an extender in the higher proportions rather than a .plasticizer.

Within the stated range of 33-100 parts for plasticizers the nature of the plasticizer selected will influence the specific amount used, that is, plasticizers having relatively lower melting points will be used generally in the lower part of the range of proportions given while the relatively higher melting point plasticizers will be used'in the higher part of the range of proportions given and, in fact, may even be used in excess of the upper limit of the proportion range. v

The modifiers found useful in the present invention include parafiin wax (preferablyof melting point of 50-59 0.), ceresin wax, and Japan wax.

Among the extenders suitable for use in the herein considered impregnating compositions may be mentioned gum rosin, wood rosin, and montan wax, all well adapted for use as the sole auxiliary ingredient in the composition, and Barrett Company's Cumar FX (melting range 125-130 C.), black East India gum, and limed rosin which are not particularly desirable as sole auxiliary ingredients because they do not depress the softening temperature of the beta naphtholmodified rubber sumciently.

The impregnating compositions of the present invention are readily formed by melting the ingredients together and, in molten condition, at temperatures low enough to cause no decomposition or degradation, are sufiiciently mobile for the impregnation of fibrous webs by ordinarily available methods.

The impregnated webs made according to the present invention are readily blanked and skived by the usual methods and do not break down to dust.

Shoe stiifening members made in accordance with the invention, upon being placed in the steamer following the standard practice, become completely limp and soft, and sticky enough to adhere to the shoe lining but not so sticky as to adhere to the operator's fingers. The limpness is retained, upon removal from the steamer, for a period entirely adequate to permit of the stretching of the piece over the last. The construction of the shoe may be carried out in the usual manner and at no stage during the wearing of the shoe does the impregnant exert any staining or other deleterious eflect upon the leather or fabric with which it is associated in the shoe.

Stifiening members made according to the present invention possess unusual rigidity and toughness in proportion to their thickness and, for this reason, are well adapted to provide adequate to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

We claim: 1. A stifi'ening member for shoes and the like, comprising a web of fibrous material impregnated with a composition comprising essentially beta naphthol-modified rubber and'a. compatible auxiliary component from the group consisting of non-volatile, water-insoluble, organic plasauxiliary component from the groupconsisting of non-volatile, water-insoluble, organic plasticizers, modifiers, and extenders.

4. An impregnating composition for shoe stiffeners and the like comprising essentially beta naphthol-modified rubber and a compatible auxiliary component from the group consisting of non-volatile, water-insoluble, organic plas- I ticizers, modifiers, and extenders, said composition having a temperature of plasticity of IO- C. and a softening point of 75-100 C. Y

5. A stiffening member for shoes and the like, comprising a web of fibrous material impregnated with a composition comprising parts beta naphthol-modified rubber and 53-100 parts of coumarone indene resin, said resin having a -melting range of from 20-45 C.

6. A stiffening member for shoes and the like. comprising a web of fibrous material impregnated with a composition comprising 100 parts beta naphthol-modified rubber, -870 parts of rosin, and 20-14! parts of coumarone indene resin, said resin having a melting range 01' from 20-45" C.

7. A stiffening member for shoes and the like, j

comprising a web of fibrous material-impregnated with a composition comprising 100 parts beta naphthol-modified rubber, 50-800 parts montan.

wax, and 18-100 parts of coumarone indene resin, said resin having a melting range of from 20-45 C.

8. An impregnating composition for shoe stiifeners and the like comprising 100 parts beta naphthol-modified rubber and 53-100 parts of coumarone indene resin, said resin having a melting range of from 20-45 C'.

9. An impregnating composition for shoe stiflfeners and the like, comprising 100 parts beta naphthol-modified rubber, 125-870 parts of rosin, and 20-147 parts of coumarone indene resin, said resin having a melting range of from 20-45" C.

10. An impregnating composition for shoe stifieners and the like, comprising 100 parts beta naphthol-modified rubber, 50-800 parts of montan wax, and 18-100 parts of coumarone indene resin, said resin having a melting range of from PAUL A. BALON. HAROLD S. HOLT. 

